The present invention relates to the steerability of a boat or craft propelled by a conventional straight line drive inboard mounted engine, which also includes "V" drive engines mounted to a straight line drive propeller shaft.
Outboard engines or "L" drive and stern power outdrive or "Z" drive have great steering advantages over conventional inboard straight line drive powered boats or crafts due to the fact that propellers of such "L" or "Z" drives can be steered in an arc about the center line of a keel of a boat thus providing an angular thrust to the stern of a boat. This thrust pushes the stern around without the necessity of propelling the boat a great distance forward as compared to the distance and area that would be required for a straight line drive propelled boat to accomplish the same turning maneuver.
Through the years this problem has become greater because every year more boats are on the waterways and harbors and marinas are becoming more crowded with less area for boats to maneuver. Bow thrusters have come in to use in some instances primarily for that reason.